2-Chloroethylphosphonodithioate esters

ABSTRACT

2-Chloroethylphosphonodithioate esters, useful as plant growth regulators for increasing fruiting having the following formula:   wherein R is alkyl of one to two carbon atoms, halo-substituted alkyl of one to two carbon atoms, aryl of six to 12 carbon atoms, halo-substituted aryl of six to 12 carbon atoms or aralkyl produced by the reaction of a 2-chloroethylphosphonyl halide with a mercaptan of the formula RSH in the presence of an acid acceptor compositions containing the same and methods for using the compositions.

United States Patent 1191 Randall et a].

1*Sept. 16, 1975 1 2-CHLOROETHYLPHOSPHONODITHIOATE ESTERS v [75]Inventors: David I. Randall; Robert W. Wynn, both of Easton, Pa.

[73] Assignee: GAF Corporation, New York, NY.

[ 1 Notice: The portion of the term of this patent subsequent to Sept.24, 1991, has been disclaimed.

[22] Filed: Jan. 17, 1972 21 Appl. NO.Z 218,527

Related US. Application Data [62] Division of Ser. No. 875,574, Nov. 10,1969, Pat. No.

OTHER PUBLICATIONS Cooke et al., Nature, Vol. 2l8, June 8, 1968, pp.

Primary Examiner-Elbert L. Roberts Assistant E.ranzirwr-Catherine L.Mills Arlurnqv, Agent, or FirmWalter C. Kehm 5 7 ABSTRACT2-Chloroethylphosphonodithioate esters, useful as plant growthregulators for increasing fruiting having the following formula:

wherein R is alkyl of one to two carbon atoms, halosubstituted alkyl ofone to two carbon atoms, aryl of six to 12 carbon atoms,halo-substituted aryl of six to 12 carbon atoms or aralkyl produced bythe reaction of a 2chloroethylphosphonyl halide with a mercaptan of theformula RSH in the presence of an acid acceptor compositions containingthe same and methods for using the compositions.

13 Claims, No Drawings 2-CHLOROETHYLPHOSPHONODITHIOATE ESTERS Thisapplication is a division of application Ser. No 875,574. filed November10, 1969, now US. Pat. No. 3,838,180.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to Z-chloroethylphosphonodithioate esters useful as plant growthregulators, processes for their preparation and procedures for theiruse.

2. Background of the Prior Art Among the various materials known in theart as being plant growth regulators, 2-chloroethylphosphonic acid hasmany valuable and unique properties. It has now been found that a narrowclass of compounds related to Zehloroethylphosphonic acid, specificallycertain thioesters of 2-chloroethylphosphonic acid, have uniquebiological activity in that they exhibit growth regulation for increasedfruiting on plants such as soy beans, pineapples and the like. Whilestructurally similar compounds are known in the art, for example, atChemical Abstracts, Vol. 51, page 4935, which disclosesS,S-dibutyl-Z-chloroethyl phosphonodithioate, prepared from the sodiumsalt of the corresponding alcohol suspended in ether and 2-chloroethylphosphonyl dichloride, such compounds have not been found to be asuseful as plant growth regulators as are those of the present invention.

SUMMARY OF THE INVENTION chloroethyl phosphonodithioate acids of thefollowing formula:

wherein R is alkyl of one to two carbon atoms, haloalkyl of one to twocarbon atoms. the halo atom being chlorine, bromine. iodine or fluorine,but preferably chlorine, aryl of six to 12 carbon atoms, phenylornaphthyl, haloaryl of six to 12 carbon atoms, or aralkyl of seven to 12carbon atoms. These compounds are produced by the reaction between al-chloroethyl phosphonyl dihalide with a mercaptan of the formula, RSH,in the presence of an acid acceptor.

DESCRIPTION OF PREFERRED EMBODIMENTS According to this invention, thereare provided cartain esters of 2chloroethyl phosphonodithioic acid whichhave been found to be useful as plant growth regulators for increasedfruiting. These compounds are of the following structure wherein in theabove formula, R is alkyl of one to two carbon atoms (ethyl or methyl),haloalkyl of one to two carbon atoms, the halo atom being chlorine,bromine, iodine or fluorine but preferably chlorine, a preferred radicalof this class being 2-chloroethyl, aryl of six to 12 carbon atoms suchas phenyl or naphthyl, including alkyl substituted derivatives thereofwherein the alkyl group has one to seven carbon atoms, halo-substitutedaryl such as 2.3, or 4-chlorophenyl, 2,3,4- chloronaphthyl,3,4-dichlorophenyl, 3.4.5- trichloi'ophcnyl, and the like or aralkyl ofseven to 12 carbon atoms, for example, benzyl.

The above compounds have been found to provide unexpectedly increasedgrowth regulation properties in that they increase fruiting of plantssuch as pineapples, soy beans, tomatoes. small grains, and the like, andthereby increase the yields thereof. The compounds are believed tooperate because of the fact that they are absorbed by the plant andrelease ethylene. a known plant regulator, in a form in which it can beused by the plant.

The compounds of this invention are soluble in varying degrees in waterand so they can be applied to the plants in aqueous solutions composedwholly or partially of water; partial solutions include those formed ofwater and say acetone or methyl ethyl ketone. Any aqueous medium may beused provided that it is not toxic to the plant.

The novel compounds of the present invention in which the R groups areethyl or methyl are particularly preferred since not only have theyexhibited higher aetivity/g, but in addition, have relatively highsolubility in water so they they can be applied to plants from anaqueous medium without the necessity of any further additives andhydrolyze relatively slowly with resultant sustained or prolongedactivity. The novel compounds in this invention, in which the R groupsare aryl. or halo-substituted aryl, or aralkyl, have substantially lesswater solubility, and, in addition, hydrolyze much more rapidly. Onecertain plants, therefore, it may be advantageous to use a mixture ofcompounds, some of which are aryl, halo-substituted aryl or aralkyl inorder to provide high initial hydrolysis and resultant activity andothers in which R is methyl or ethyl, to provide sustained or prolongedhydrolysis and resultant activity.

In the case of those particular derivatives which have relatively slowwater solubility, they may be solubilized by the use of co-solvents andthe like. Also, the com pounds may be adsorbed on solid carriers such as\'er miculite, attaclay, talc and the like for application in granularform. Dusts may also be used in which case the active ingredients willbediluted with clays or other powders, for example pyrophyllite.diatomaceous earth and attapulgite.

The compounds of this invention can be applied to the plants at aconcentration of from /2 to 10 lbs/acre or higher. dependent on theparticular derivative used. A preferred rate of application ranges from2-5 lbs/acre. The phosphonic derivaties need only be applied to theplant in low volumes of water to achieve satisfactory initiation, andthis is'an important advantage of this invention. Whereas it isnecessary to apply the known agents in large volumes of water. of theorder of 200400 gallons/acre. even up to 1.000 galions/acre in the caseof ethylene to achieve initiation. it is possible to apply a compound ofthis invention in far lower volumes of water to achieve satisfactoryflower initiation. For example, the compoundsof the present inventioncan be applied in 50 gallons of water at the rate of l lb./acre toachieve 100% flower induction on pineapples of the Smooth Cayennevariety. The ability -to apply the agent in a reduced volume of water isa great agronomic advantage because a large acreage of plantation can betreated before recourse to a water supply is necessary. smallerequipment can be used and costs can'be reduced generally.

The products of this invention are prepared by reaction between oneequivalent of a 2-chloroethyl phos phonyl dihalide of the followingformula:

wherein X is halogen. preferably chlorine. with at least two equivalentsof a mercaptan of the formula. RSH. wherein R is as defined above. inthe presence of two equivalents of an acid acceptor. The acid acceptorsemployed are those generally known in the art such as tertiary amines.e.g.. triethylamine. trimethylaminc. pyridine. etc. as well as inorganicacceptors such as alkali metal hydroxides (cg. NaOH or KOH alkali metalcarbonates (e.g.. Nil- C0 alkali metal bicarbonates (NaHCOo. etc.Mixtures may also be used. Obviously any other acid acceptor known tothose skilled in the art may be employed.

Suitable mercaptans which may be employed to provide the final productsinclude ethyl mercaptan. methyl mercaptan. p-t-butylphenyl mercaptan.p-chlorophenyl mercaptan. benzyl mercaptan and the like.

The reaction is generally conducted at low temperatures and preferablyin an inert solvent which has had substantially 'all the water removedtherefrom. Preferred temperatures of operation are about l0 to 20C. andpreferably from 05(. A preferred solvent for use in the invention isdried diethyl ether although other equivalent solvents may be employed,such as aromatic hydrocarbons (e.g.. benzene. toluene and xylene).dioXane. and the like. i

In conducting the process. the phosphorus compound insolvent solution isgenerally charged to a reactor and the substituted mercaptan. also inthe solvent solution. added thereto followed by addition of the acidacceptor. which is preferably also added in solvent solution. After allthe materials are added at the lowtcmperatures. the reaction mixture isthen permitted to warm to room temperature and agitated for a shortperiod of time to allow the reaction to go to complctit'vn."

Thereafter. the salt formed during the reaction is filtered off and theresulting filtrate distilled or otherwise processed to provide theproduct as a residue.

The following examples are presented to further illustrate the inventionbut it is not be be considered as limited thereto.

EXAMPLE 1 S.S-Diethyl 2-Chloroethylphosphonodithioate There were chargedto a reaction flask 27.3 grams (0. 15 mole )of 2-ehloroethylphosphonyldichloride and 200 ml. anhydrous ether. At a temperature of O5C. therewas added dropwise a solution of 18.6 grams (0.3 mole) ethyl mercaptanin 50 ml. anhydrous ether followed by a solution of 30.3 grams (0.3mole) triethylamine in 50 ml. anhydrous ether. After stirring at roomtemperature for one hour, the amine hydrochloride was filtered off'andwashed with ether. The filtrate was freed of solvent by flashevaporation to yield a residue of 33.7 grams. This product was distilledunder vacuum. A 17.2 gram fraction of clear liquid boiling at 8285C.under 0.05 mm. pressure was collected.

Analysis CaIc'd. Found I C.;H (I(.)PS. I? (l 15.27 14.88 S 27.527.3!12725 EXAMPLE 2 I S.S-Diphenyl-2-ChloroethylphosphonodithioateEXAMPLE 3 S.S-Di-( p-tert-butylphenyl )-2-ChloroethylphosphonodithioateIn a manner similar to Example 2 above the same molar quantities of2-chlo'roethylphosphonyl dichloride and triethylamine were reacted with33.2 grams (0.2 mole) p-tert-butylphenylmercaptan to yield a whitecrystalline product. S.S-di( p-tert-butylphenyi )-2-chliiroethylphosphonodithioate.

EXAMPLE 4 S.S-Di-( p-chlorophenyl )-2-Chloroethylphosphonodithioate in amanner similar to Example 2 the product from p-ehloro-phenylmcrcaptanand 2-chloroethylphosphonyl dichloride was obtained. This compound hadthe followingformula: l l

EXAMPLE 5 S,S-Dibenzyl-2-Chloroethylphosphonodithioate In a mannersimilar to Example 2, the reaction of ptoluenethiol and2chloroethylphosphonyl dichloride yieldedS,S-dibenzyl-2-chloroethylphosphonodithioate.

The invention has been described herein with reference to certainpreferred embodiments but obvious variations thereon will become obviousto those skilled in the art.

What is claimed is:

l. A plant growth regulating composition far increasing fruiting inplants which comprises an inert carrier and a plant growth regulatingamount of an ester of 2- chloroethylphosphonodithioic acid of theformula:

wherein R is alkyl of one to two carbon atoms, halo-alkyl of one to twocarbon atoms, aryl of six to 12 carbon atoms, halosubstituted aryl ofsix to 12 carbon atoms, alkyl-substitutcd aryl of six to 12 carbon atomswherein the alkyl group contains one to seven carbon atoms or aralkyl ofseven to 12 carbon atoms and mixtures of said esters.

2. A plant growth regulating composition according to claim 1 whereinsaid carrier is a liquid.

3. A plant growth regulating composition according to claim 2 whereinsaid carrier is water.

4. A plant growth regulating composition according to claim I whereinsaid carrier is a solid.

5. A plant growth regulating composition according to claim 1 whereinsaid ester is S.S-diethyl-2- chloroethylphosphonodithioatc.

6. A plant growth regulating composition according to claim 1 whereinsaid ester is S,Sdiphenyl-2- chloroethylphosphonodithioatc.

7. A plant growth regulating composition according to claim 1 whereinsaid ester is S,S(p-t.butylphenyl)-2- chloroethylphosphonodithioate.

8. A plant growth regulating composition according to claim 1 whereinsaid ester is S,S-di-(p chlorophenyl )-2-chloroethylphosphonodithioate.

9. A plant growth regulating composition according to claim 1 whereinsaid ester is S,S-dibenzyl-2- chloroethylphosphonodithioatc.

10. The method for regulating plant growth for in' creasing fruiting inplants which comprises contacting said plants with a compositionaccording to claim 1.

11. A method according to claim 10 which comprises utilizing saidcomposition in an amount from V; to 10 pounds per acre.

12. A method according to claim 10 which comprises utilizing saidcomposition in an amount from 2 to 5 pounds per acre.

13. A method according to claim 10 which comprises utilizing saidcomposition at the rate of 1 pound per acre in about 50 gallons ofwater.

1. A PLANT GROWTH REGULATING COMPOSITION FAR INCREASING FRUITING INPLANTS WHICH COMPRISES AN INERT CARRIER AND A PLANT GROWTH REGULATINGAMOUNT OF AN ESTER OF 2-CHLORETHYLPHOSPHONODITHIOIC ACID OF THE FORMULA:2. A plant growth regulating composition according to claim 1 whereinsaid carrier is a liquid.
 3. A plant growth regulating compositionaccording to claim 2 wherein said carrier is water.
 4. A plant growthregulating composition according to claim 1 wherein said carrier is asolid.
 5. A plant growth regulating composition according to claim 1wherein said ester is S,S-diethyl-2-chloroethylphosphonodithioate.
 6. Aplant growth regulating composition according to claim 1 wherein saidester is S,S-diphenyl-2-chloroethylphosphonodithioate.
 7. A plant growthregulating composition according to claim 1 wherein said ester isS,S-(p-t.butylphenyl)-2-chloroethylphosphonodithioate.
 8. A plant growthregulating composition according to claim 1 wherein said ester isS,S-di-(p-chlorophenyl)-2-chloroethylphosphonodithioate.
 9. A plantgrowth regulating composition according to claim 1 wherein said ester isS,S-dibenzyl-2-chloroethylphosphonodithioate.
 10. The method forregulating plant growth for increasing fruiting in plants whichcomprises contacting said plants with a composition according toclaim
 1. 11. A method according to claim 10 which comprises utilizingsaid composition in an amount from 1/2 to 10 pounds per acre.
 12. Amethod according to claim 10 which comprises utilizing said compositionin an amount from 2 to 5 pounds per acre.
 13. A method according toclaim 10 which comprises utilizing said composition at the rate of 1poUnd per acre in about 50 gallons of water.